Tailoring of onboard system software

Tailoring of an operating system and an in embedded real-time operating system in particular is es-sential for both, kernel and operation. But many of current embedded real-time operating systems provide somebasic tailoring at the cost of depleting the flexibility of hardware, which causes the lack of flexibility, and de-grades their tailors. A layered modular tailoring model has been proposed together with some tailoring operationsto improve the flexibility of the systems, and algorithms have been proposed for verification of tailoring opera-tions with the current operating system.

Big Data Application Simulation Platform Design for Onboard Distributed Processing of LEO Mega-Constellation Networks

Due to the restricted satellite payloads in LEO mega-constellation networks(LMCNs),remote sensing image analysis,online learning and other big data services desirably need onboard distributed processing(OBDP).In existing technologies,the efficiency of big data applications(BDAs)in distributed systems hinges on the stable-state and low-latency links between worker nodes.However,LMCNs with high-dynamic nodes and long-distance links can not provide the above conditions,which makes the performance of OBDP hard to be intuitively measured.To bridge this gap,a multidimensional simulation platform is indispensable that can simulate the network environment of LMCNs and put BDAs in it for performance testing.Using STK's APIs and parallel computing framework,we achieve real-time simulation for thousands of satellite nodes,which are mapped as application nodes through software defined network(SDN)and container technologies.We elaborate the architecture and mechanism of the simulation platform,and take the Starlink and Hadoop as realistic examples for simulations.The results indicate that LMCNs have dynamic end-to-end latency which fluctuates periodically with the constellation movement.Compared to ground data center networks(GDCNs),LMCNs deteriorate the computing and storage job throughput,which can be alleviated by the utilization of erasure codes and data flow scheduling of worker nodes.

Investigations of the mechanical response of dummy HTPB propellant grain under ultrahigh acceleration overload conditions using onboard flight-test measurements

In this paper,to study the mechanical responses of a solid propellant subjected to ultrahigh acceleration overload during the gun-launch process,specifically designed projectile flight tests with an onboard measurement system were performed.Two projectiles containing dummy HTPB propellant grains were successfully recovered after the flight tests with an ultrahigh acceleration overload value of 8100 g.The onboard-measured time-resolved axial displacement,contact stress and overload values were successfully obtained and analysed.Uniaxial compression tests of the dummy HTPB propellant used in the gunlaunched tests were carried out at low and intermediate strain rates to characterize the propellant's dynamic properties.A linear viscoelastic constitutive model was employed and applied in finite-element simulations of the projectile-launching process.During the launch process,the dummy propellant grain exhibited large deformation due to the high acceleration overload,possibly leading to friction between the motor case and propellant grain.The calculated contact stress showed good agreement with the experimental results,though discrepancies in the overall displacement of the dummy propellant grain were observed.The dynamic mechanical response process of the dummy propellant grain was analysed in detail.The results can be used to estimate the structural integrity of the analysed dummy propellant grain during the gun-launch process.

Design on Model-based Visualization System for Civil Aircraft Airborne Equipment Identification Test

To meet the needs of complex system equipment testing and realize the visual management of different test projects,this article establishes a test project management system based on the actual situation of aviation equipment testing system and the concept of big data,using visual data management and analysis techniques.This system solves the comprehensive management of multi-type test projects.Combined with the actual engineering verification process,it can be found that the system can realize the visual management of test projects and effectively ensure the smooth completion of the identification test project of a certain type of aircraft′s complex system.

MODELING AND NUMERICAL SIMULATION OF ONBOARD MOLECULAR SIEVE OXYGEN GENERATION SYSTEM

A mathematical model for simulating concentric-bed and other components of molecular sieve oxygen concentrator is established. In the model, the binary Langmuir equilibrium adsorption equation is adopted to describe the adsorption performance of the adsorbent, the linear driving force (LDF) model is used to describe the mass transfer rate, and the thermal effect during adsorption is considered. The finite difference method is used in simulation and comparison. Numerical results have a reasonable agreement with the experimental research.

Design of Central Management & Control Unit for Onboard High-Speed Data Handling System

The Main Optical Telescope (MOT) is an important payload of the Space Solar Telescope (SST) with various instruments and observation modes. Its real-time data handling and management and control tasks are arduous. Based on the advanced techniques of foreign countries, an improved structure of onboard data handling systems feasible for SST, is proposed. This article concentrated on the development of a Central Management & Control Unit (MCU) based on FPGA and DSP. Through reconfigurating the FPGA and DSP programs, the prototype could perform different tasks. Thus the inheritability of the whole system is improved. The completed dual-channel prototype proves that the system meets all requirements of the MOT. Its high reliability and safety features also meet the requirements under harsh conditions such as mine detection.

Omnidirectional Antenna Diversity System for High-Speed Onboard Communication

In this article,an omnidirectional dual-polarized antenna with synergetic electromagnetic and aerodynamic properties is propounded for high-speed diversity systems.The propounded antenna comprises a probe-fed cavity for horizontally polarized radiation and a microstrip-fed slot for vertical polarization.Double-layer metasurfaces are properly designed as artificial magnetic conductor boundaries with direct metal-mountable onboard installation and compact sizes.An attached wedge-shaped block is utilized for windage reduction in hydrodynamics.The propounded antenna is fabricated for design verification,and the experimental results agree well with the simulated ones.For vertical polarization,the operating bandwidth is in the range of 2.37–2.55 GHz,and the realized gain variation in the azimuthal radiation pattern is 3.67 decibels(dB).While an impedance bandwidth in the range of 2.45–2.47 GHz and a gain variation of 3.71 dB are also achieved for horizontal polarization.A port isolation more than 33 dB is obtained in a compact volume of 0.247λ_(0)×0.345λ_(0)×0.074λ_(0),whereλ_(0)represents the wavelength in vacuum at the center frequency,wherein the wedge-shaped block is included.The propounded diversity antenna has electromagnetic and aerodynamic merits,and exhibits an excellent potential for high-speed onboard communication.

服务天基感知业务的卫星互联网模拟验证系统设计与分析

提出具有遥感、星间星地组网、星载边缘计算功能的低轨卫星与地面云计算中心和天基、临近空间、空中、陆地、海面等各类型终端构成的卫星互联网总体架构,给出包括资源层、虚拟化层、服务层、服务管理层及应用层在内的星载边缘计算功能架构。针对星载计算能力有限、天基网络拓扑高动态等典型特征,在提出星载边缘计算模拟验证系统构建方法的基础上,设计服务天基感知业务的卫星互联网模拟验证系统,开展天基感知信息处理分发试验,并根据不同信息处理与分发方式对网络资源占用和用户服务时延的对比,分析不同能力条件下卫星互联网对天基感知业务服务的能力水平。

基于AUTBUS总线的机载无线柔性分布式测试系统数据同步采集技术

本研究致力于机载无线柔性分布式测试系统的研制,以解决在飞行试验中测试系统占地空间大、线缆使用量大、走线复杂、测试通道数量多等问题。分布式系统的节点分布在不同的位置,其内部时钟可能因多种因素而出现不同步的情况,从而影响数据采集的精度。通过灵活的时隙资源分配机制实现AUTBUS总线的动态调整,确保系统通信的高效稳定。采用1PPS、TOD及AUTBUS总线对表算法,系统能够有效地实现全网节点设备的时间同步,确保各个节点在相同的时间基准上进行协同操作。测试数据同步采集基于外部触发的模数转换模块,在全网协同事件的时刻实现各节点数据的同步采集。测试结果表明系统的同步数据采集精度最低为822.5 ns,满足飞行试验中机载测试的数据采集需求。

GB/T 26990-2023《燃料电池电动汽车车载氢系统技术条件》标准分析

近年来随着燃料电池电动汽车技术不断升级,与35 MPa车载氢系统相比,公称压力为70 MPa的车载氢系统具有储氢体积密度大可提高整车续驶里程的优点,在乘用车上得到广泛应用。而在GB/T 26990—2011《燃料电池电动汽车车载氢系统技术条件》及GB/T 29126—2012《燃料电池电动汽车车载氢系统试验方法》中仅适用于公称工作压力不超过35 MPa的车载氢系统,而且该版标准已实施十余年,已不能完全适应现阶段燃料电池电动汽车车载氢系统技术现状,因此2023年11月,我国发布了GB/T 26990—2023《燃料电池电动汽车车载氢系统技术条件》,该标准修改和增加了部分技术内容以适应当前燃料电池电动汽车行业发展水平。本文将阐述GB/T 26990—2023的主要技术内容及其与上一版标准的异同,并对新标准中相关技术内容和测试方法进行解析,供行业内企业参考。

基于模型演化的列控车载设备组合测试案例重构方法

车载设备作为列控系统的关键设备之一,其测试需求在不断迭代。测试案例重构通过更新原有组合测试集覆盖变更的测试需求,实现对测试案例的高效重用,对生成演化后的测试集具有重要意义。根据车载设备输入模型的变化情况,提出一种基于模型演化的测试集重构方法。首先,通过比较演化前后组合模型的差异性,辨识出失效和新增的测试需求,并结合测试参数、参数取值、约束可能出现的演化情况分析两类测试需求的具体构成;其次,基于演化后的组合模型,依次采取修改、扩充、新增3个步骤重构原有测试集,修改不满足变更测试需求的原有案例,扩充新增参数取值,新增案例覆盖剩余测试需求;之后,根据约束间的相容性,将互不干扰的多条约束置于1条测试案例集中处理以精简测试集;最终,得到完备覆盖所有演化后测试需求的组合测试集。以车载设备模式转换等3种场景为例,对本方法进行了验证,研究结果表明:相较于现有方法,本方法能更充分地重用原有案例,测试集总体重合度提高了7.82%,后续人工修改测试案例文档的工作量相应减少,时间成本可降低18.26%。

燃料电池汽车车载氢系统潜在失效模式及原因分析

车载氢系统的安全性是燃料电池汽车(FCV)的核心技术指标之一,其安全性保障是实现FCV大规模商业化的重要前提。本文围绕车载氢系统的安全性,介绍了车载氢系统的组成,分析了车载氢系统及其零部件的失效模式及原因,总结了车载氢系统的失效后果,并探讨了现阶段在FCV消防安全方面亟需完善的内容。分析表明,车载氢系统的潜在失效模式及原因主要包括密封、振动疲劳、机械冲击、碰撞、快速充放氢疲劳、热损伤、控制系统功能失效等,失效的主要后果表现为氢气泄漏。对于氢气泄漏的危害分析应充分结合车辆所处的场景进行综合考量,在极端场景下,“氢气泄漏+密闭/半密闭空间+点火源”将引起火灾甚至爆炸,会严重威胁公众的生命财产安全。因此,建议从强化安全性设计和验证、提升氢泄漏监测和气源控制技术、开展失效致灾危害量化评价、加强火灾防控技术等多个方面,促进车载氢系统的安全性水平提升。

车载ATO系统记录板数据解析工具设计

为实现对列车记录数据的读取、解析与显示,便于数据分析和列控系统的后期维护,开发车载自动驾驶(Automatic Train Operation,ATO)系统记录板数据解析工具。在对车载ATO系统记录板数据解析工具需求规范进行深入分析的基础上,明确解析工具的各项具体功能,给出软件的总体设计思路及各功能的详细设计流程,最后介绍软件的使用方法,为后续用户使用提供指导。同时基于实测数据对软件功能进行测试验证。测试结果表明,所开发的解析工具可完全实现设计功能,且操作便捷。

基于分布式技术的动车组车载大数据存储与检索技术研究

随着动车组的数据传输能力升级改造以及复兴号智能型动车组的上线运营,动车组监测项点数据快速扩充,如何高效、准确地对动车组的海量车载非实时数据进行存储、检索与查询,成为提升动车组车载数据管理和应用水平面临的一个挑战。文中提出一种基于分布式技术的海量非实时数据地面系统架构,将各动车运用所的数据服务站点作为子节点,全路数据服务中心作为主节点,对具备时空属性的海量数据快速检索算法进行了研究,构建了一种支持分布式数据存储、检索及数据分析的架构,开发了原型系统,验证了解决方案的可行性和有效性。

基于STAMP与组合测试的城轨全自动运行系统车载设备安全测试方法研究

针对现有城轨全自动运行系统车载设备测试安全性需求考虑不足与测试用例规模较大的问题,提出一种基于STAMP理论与组合测试的城轨全自动运行系统车载设备安全性测试方法。首先,基于STAMP理论对车载设备建立分层控制结构模型,从可测性的角度提取出安全约束,分析安全约束涵盖的车载设备安全性测试特征;然后,以最优覆盖数组与种子测试用例为基础,结合约束条件,利用遗传算法对最优覆盖数组进行重构,扩展生成满足约束条件的精简测试用例集;最后,以全自动运行系统站台发车场景车载设备测试为例,对算法有效性进行验证。结果表明,在组合覆盖强度相同的情况下,本文方法比现有主流方法生成的测试用例数平均降低16.45%,对降低车载设备测试成本、提升测试效率具有一定现实意义。

集成型车载充电系统并网模式模型预测控制策略

相较于传统车载充电系统,集成型车载充电系统(integrated onboard charger system,IOCS)在成本、功率密度等方面具备显著优势。文中基于六相永磁电驱系统设计了一台IOCS,并研究了模型预测电流控制(model predictive current control,MPCC)算法在该系统并网模式下的应用。首先,分析所提IOCS的电路拓扑并建立数学模型,同时介绍传统MPCC的实施流程。然后,针对传统MPCC计算量大、稳态性能差等不足,提出一种基于占空比优化的MPCC(MPCC based on duty cycle optimization,DCO-MPCC)策略。一方面,减少备选电压矢量数量,降低电流预测环节带来的计算负担;另一方面,提出一种占空比优化技术,改善系统稳态性能。最后,通过实验验证了所提算法的有效性与优越性。实验结果表明,DCO-MPCC策略能够显著提升系统稳态性能并减少算法计算量。充电与车网互动(vehicle to grid,V2G)工况下,网侧电流总谐波畸变(total harmonic distortion,THD)分别降低6.18%与5.92%,算法运行时间减少17.54μs。

面向能效设计指数的LNG燃料船CO_(2)捕集系统设计及性能分析

为满足国际海事组织(International Maritime Organization,IMO)第三阶段船舶能效设计指数(energy efficiency design index,EEDI)的要求,提出一种液化天然气(liquefied natural gas,LNG)燃料船船载碳捕集系统(onboard carbon capture system,OCCS)。OCCS通过醇胺溶液对主机烟气中的CO_(2)进行富集,并回收主机烟气余热用于醇胺溶液再生,再利用LNG汽化过程中释放的冷能对解吸出的CO_(2)进行液化。以一艘Kamsarmax型船为例,构建基于冷热能综合利用的OCCS模型,分析烟气质量流量、溶剂质量流量和吸收塔进口处的贫液温度对CO_(2)捕集量及比热耗的影响。结果表明:提高贫液温度能够有效减少热量消耗,烟气和溶剂质量流量对CO_(2)捕集量影响显著,当溶剂质量流量大于18000 kg/h时,OCCS能满足IMO第三阶段的CO_(2)减排要求。该船通过所设计的OCCS可以满足IMO第三阶段EEDI的要求,其比热耗在10.9~12.2 GJ/t范围内。

35 MPa车载氢系统减压阀失效仿真研究

车载氢系统的安全和稳定对氢能车的正常运行非常重要,一旦其中的部件失效,可能会引发重大的安全事故。减压阀作为车载氢系统的核心部件之一,常常会受氢气的高压或高低温环境的影响而失效,导致无法正常减压,甚至会造成氢气泄漏。要使减压阀能够正常地将氢气减压到指定压力,使燃料电池正常工作,往往需要对其进行高低温环境耐压测试,以确保其结构设计合格。对减压阀进行高低温耦合动力学仿真,以验证其结构设计是否合格,并根据仿真结果提出相关优化结构和预防失效的指导建议。

基于轨道不平顺匹配的多源融合列车定位方法

列车定位是保障铁路安全高效运营的基础,面向先进列车运行控制系统高精度、连续、可靠的位置服务需求,研究高精度、高可靠、低成本的匹配定位源提升列车定位系统的稳健性和准确度具有重要的现实意义。本文提出一种无布设轨道特征信号-轨道不平顺,利用惯性导航系统感知和测量轨道不平顺信号实现匹配定位,结合列车运动约束,实现了无布设情况下的全自主、全天候、全地域的连续可靠的组合定位。为了验证该方案的可行性,本文在真实铁路线路上进行了列车车载试验。试验结果表明:一个典型的战术级IMU可以实现0.6 m(98.46%置信度)的列车定位精度。该方法为多传感器融合的列车定位系统提供了一种新的定位信号源,可以用于提高车载列车定位系统的准确性和稳健性。

城市轨道交通信号车辆接口的通用统型方案

[目的]信号系统升级改造难度大、费用高、周期长,改造阶段对线路的日常运营也有较大的影响。为解决上述问题,应对信号车辆接口进行统型。[方法]通过对不同信号系统的安装接口进行分析,提出了兼容的信号车辆安装接口平台。基于车载信号系统的组成及功能,重点对信号车辆的机械安装接口统型、电气及控制接口统型、网络接口统型3个类别进行了研究,提出了不同设备接口的通用统型方案。[结果及结论]该方案可在很大程度上匹配不同信号厂家的设备安装需求。新信号系统设备安装时,既有车辆安装平台接口不需要大幅变动。该方案可以有效降低信号系统升级改造的难度,减少改造费用,提高改造效率。